Bowed legs

Rickets

[rik-its]

Rickets is a softening of the bones in children potentially leading to fractures and deformity. Rickets is among the most frequent childhood diseases in many developing countries. The predominant cause is a vitamin D deficiency, but lack of adequate calcium in the diet may also lead to rickets. Although it can occur in adults, the majority of cases occur in children suffering from severe malnutrition, usually resulting from famine or starvation during the early stages of childhood. Osteomalacia is the term used to describe a similar condition occurring in adults, generally due to a deficiency of vitamin D. The origin of the word "rickets" is probably from the Old English dialect word 'wrickken', to twist. The Greek derived word "rachitis" (meaning "inflammation of the spine") was later adopted as the scientific term for rickets, due chiefly to the words' similarity in sound.

Epidemiology

Those at higher risk for developing rickets include:

Breast-fed infants whose mothers are not exposed to sunlight
Breast-fed infants who are not exposed to sunlight
Individuals not consuming fortified milk, such as those who are lactose intolerant

Individuals with red hair have been speculated to have a decreased risk for rickets due to their greater production of vitamin D in sunlight.

Etiology

Vitamin D is required for proper calcium absorption from the gut. In the absence of vitamin D, dietary calcium is not properly absorbed, resulting in hypocalcemia, leading to skeletal and dental deformities and neuromuscular symptoms, e.g. hyperexcitability.

A rare X-linked dominant form exists called Vitamin D resistant rickets.

Presentation

Signs and symptoms of rickets include:

Bone pain or tenderness
dental problems
muscle weakness (rickety myopathy or "floppy baby syndrome")
increased tendency for fractures (easily broken bones), especially greenstick fractures
Skeletal deformity

Toddlers: Bowed legs (genu varum)
Older children: Knock-knees (genu valgum) or "windswept knees"
Cranial, spinal, and pelvic deformities

Growth disturbance
Hypocalcemia (low level of calcium in the blood), and
Tetany (uncontrolled muscle spasms all over the body).
Craniotabes (soft skull)
Costochondral swelling (aka "rickety rosary" or "rachitic rosary")
Harrison's groove
Double malleoli sign due to metaphyseal hyperplasia

An X-ray or radiograph of an advanced sufferer from rickets tends to present in a classic way: bow legs (outward curve of long bone of the legs) and a deformed chest. Changes in the skull also occur causing a distinctive "square headed" appearance. These deformities persist into adult life if not treated.

Long-term consequences include permanent bends or disfiguration of the long bones, and a curved back.

Diagnosis

A doctor may diagnose rickets by:

Blood tests:

Serum calcium may show low levels of calcium, serum phosphorus may be low, and serum alkaline phosphatase may be high.

Arterial blood gases may reveal metabolic acidosis
X-rays of affected bones may show loss of calcium from bones or changes in the shape or structure of the bones.
Bone biopsy is rarely performed but will confirm rickets.

Treatment and prevention

The treatment and prevention of rickets is known as antirachitic.

Diet and sunlight

Treatment involves increasing dietary intake of calcium, phosphates and vitamin D. Exposure to ultraviolet light (sunshine), cod liver oil, halibut-liver oil, and viosterol are all sources of vitamin D.

A sufficient amount of ultraviolet in sunlight each day and adequate supplies of calcium and phosphorus in the diet can prevent rickets. Darker-skinned babies need to be exposed longer to the ultraviolet rays. The replacement of vitamin D has been proven to correct rickets using these methods of ultraviolet light therapy and medicine.

Recommendations are for 200 international units (IU) of vitamin D a day for infants and children. Children who do not get adequate amounts of vitamin D are at increased risk of rickets. Vitamin D is essential for allowing the body to uptake calcium for use in proper bone calcification and maintenance.

Supplementation

Sufficient vitamin D levels can also be achieved through dietary supplementation. Vitamin D3 (cholecalciferol) is the preferred form since it is more readily absorbed than vitamin D2. Most dermatologists recommend vitamin D supplementation as an alternative to unprotected ultraviolet exposure due to the increased risk of skin cancer associated with sun exposure. Note that in July in New York City at noon with the sun out, a white male in tee shirt and shorts will produce 20,000 I.U Vitamin D from 20 minutes of non-sunscreen sun exposure.

According to the American Academy of Pediatrics (AAP), infants who are breast-fed may not get enough vitamin D from breast milk alone. For this reason, the AAP recommends that infants who are exclusively breast-fed receive daily supplements of vitamin D from age 2 months until they start drinking at least 17 ounces of vitamin D-fortified milk or formula a day. This requirement for supplemental vitamin D is not a defect in the evolution of human breastmilk but is instead a result of the modern-day infant's decreased exposure to sunlight.